The overall objective of the proposed research is to characterize the role of conjunctiva-associated lymphoid tissue (CALT) in mucosal immunity. We hypothesize that CALT of turkeys, and analogous tissues in rabbits and other mammals, has a major role in the induction of mucosal immunity to pathogens of conjunctival and upper respiratory mucosae. A major test of this hypothesis will be to determine if CALT or turkeys has structural and functional characteristics similar to classic mucosa-associated lymphoid tissues (e.g. Peyer's patches, bursa of Fabricius). Specific aims of the proposed research are: 1. to characterize the gross, histologic, and ultrastructural morphology of CALT in turkeys, 2. to determine whether CALT of turkeys functions in the uptake, translocation, and processing of macromolecular antigens, 3. to characterize populations of T and B lymphocytes and class II major histocompatibility complex proteins in CALT of turkeys, and 4. to determine the mucosal distribution, antigenic specificity, and immunoglobulin isotype of plasma cells generated in response to selected antigens presented to the conjunctival sac. These aims will be accomplished using modern morphologic, immunohistologic, autoradiographic, and computerized image analytic techniques. Bordetellosis in turkeys provides an excellent model for the study of mucosal immune responses to ocular and respiratory pathogens. Induction of mucosal immunity, by application of antigens directly to the conjunctival sac, may be an effective and practical means to generate protective mucosal immunity in ocular, pharyngeal, oral, and respiratory tissues. In humans, such an approach may be useful with mucosal vaccines for cold viruses, influenza, pertussis, mycoplasmosis, streptococcal pharyngitis, and trachoma.